How to know if the user is using multiple monitors

Question

I'm trying to figure out a way to know if the user is using multiple monitors.

I would like to know how to do this in native C++ (using the Win32 API) and with managed code (using the .NET Framework).

Thanks in advance

some very elegant Linq code in C# here by Rob Fonseca-Ensor which will calculate the bounds of all current screens in use : stackoverflow.com/questions/2176648/… — BillW
– BillW, Commented Feb 8, 2010 at 7:56

Cory Charlton · Accepted Answer · 2010-02-08 05:21:36Z

12

I can give you C# .NET:

if (Screen.AllScreens.Length > 1)
{
    // Multiple monitors
}

Edit: A search on Google turned up the following. It mentions 98/ME so it might no be relevant but may point you in the right direction:

There are new APIs for handling multiple monitors in Windows 98. The APIs used in the monitors class sample are GetMonitorInfo, MonitorFromWindow and MonitorFromRect.

The GetSystemMetrics API has some new constants (see below) that can be used to determine the metrics of a multiple monitor system. The GetSystemMetrics API returns information about the Windows environment. This API can be used to determine how many monitors are on the system, whether they are set at the same display format, and the size of the virtual desktop.

http://support.microsoft.com/kb/194578

edited Feb 8, 2010 at 5:21

answered Feb 8, 2010 at 5:09

Cory Charlton

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1 Comment

Raphael Over a year ago

Thank you. Both answers were accurate. I was able to get the number of monitors using the GetSystemMetrics function passing as argument the SM_CMONITORS constant.

Kornel Kisielewicz · Accepted Answer · 2010-02-08 05:24:44Z

6

GetSystemMetrics with SM_CMONITORS and off you go...

answered Feb 8, 2010 at 5:24

Kornel Kisielewicz

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2 Comments

Nick Bedford Over a year ago

Had a feeling it was GetSystemMetrics.

Kornel Kisielewicz Over a year ago

Using three monitors on a daily basis I needed to learn this fast ;>

Dan Herbert · Accepted Answer · 2010-02-08 05:28:06Z

6

In .NET it's as simple as using the Screen.AllScreens.Length property. Not too sure about C++ though.

edited Feb 8, 2010 at 5:28

Dan Herbert

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answered Feb 8, 2010 at 5:09

Nick Bedford

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Raphael · Accepted Answer · 2010-02-08 10:06:05Z

2

Just to document here the C/C++ solution:

int iMonitors = GetSystemMetrics(SM_MONITORS);

answered Feb 8, 2010 at 10:06

Raphael

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